1. Technical Field
The present invention relates to a data processing apparatus, an image processing apparatus and a method therefor, for embedding additional information, such as copyright information, in object data, such as image data or audio data. More particularly, the present invention is directed to a data processing apparatus, an image processing apparatus and a method therefor, for appropriately selecting from a plurality of candidate data sets, in accordance with object data contents, optimal watermark data that while ordinarily indiscernible can be easily detected, and for embedding the watermark data in the object data.
2. Prior Art
In International Publication No. WO 97/49235, for example, a system is disclosed for employing pixel block coding (PBC) to embed copyright information (also generally referred to, hereinafter, as verification data) in object data, such as image data, so that it is not visually discernible (the system for embedding verification data in content data so that it is not visually discernible is also, hereinafter, called an “electronic watermarking system).
In International Publication No. WO 98/116928 a method is disclosed for employing the electronic watermarking system disclosed in document 1 to inhibit the alteration of image data and to effectively protect literary materials.
In Japanese Unexamined Patent Publication No. Hei 10-164549, an improvement, to the electronic watermarking method in document 1, is disclosed for verifying indivisible embedded watermark data in order to detect the alteration of image data. In addition to these documents, an invention concerning the electronic watermarking system is disclosed in Japanese Unexamined Patent Publications Nos. Hei 09-151747, Hei 10-83310, Hei 10-106149, Hei 10-161933, Hei 10-164349, Hei 10-285562, Hei 10-334272, Hei 10-240626 and Hei 10-240129, and U.S. Pat. No. 5,315,448 (Japanese Patent No. Hei 8-507912), U.S. Pat. No. 5,745,604, U.S. Pat. No. 5,768,426, U.S. Pat. No. 5,850,481 and U.S. Pat. No. 5,832,119.
However, excluding one part of these documents, a method is not disclosed for optimizing watermark data in accordance with the contents of object data, e.g., the quality of the images provided by image data, and for embedding the optimized watermark data.
Further, while one part of these documents carries a description concerning a method, in accordance with the contents of an image, for changing watermark data that is to be embedded, the methods disclosed in the documents are less compatible with the properties of the data that are to be embedded, and thus, the watermark data can not be satisfactorily optimized.
To resolve the conventional problem, it is highly desirable to provide a data processing apparatus, and a method therefor, for optimizing watermark data that indicate the presence of additional information, such as copyright information, in accordance with the contents of object data, and for embedding the optimized watermark data.
It is further highly desirable to provide an image processing apparatus, and a method therefor, for optimizing watermark data in accordance with the quality of image data, such as the property of an object, so that watermark data that is less noticeable but is easily detectable can be employed to perform embedding.